Florence , Italy -LRB- CNN -RRB- -- Amanda Knox vowed Friday to fight her conviction for the murder of British student Meredith Kercher `` until the very end '' and said she `` will never go willingly '' back to Italy .

Speaking on ABC 's `` Good Morning America , '' Knox said news of the guilty verdict Thursday `` really has hit me like a train . ''

`` I did not expect this to happen . I really expected so much better from the Italian justice system , '' she said . `` They found me innocent before . How can they say that it 's guilt beyond a reasonable doubt ? ''

An appeals court found Knox and her former boyfriend , Raffaele Sollecito , guilty of murder in the Italian city of Florence after a retrial .

Her attorney , Ted Simon , told CNN 's `` New Day '' that he had been in touch with Knox and her family all day as they awaited the court 's decision .

`` It was terrible news , '' he said . `` She understands more than anyone that a wrongful conviction is unjust , not just for the accused but for the victim , their family , as well as society , and she feels this very personally . ''

Knox 's conviction has raised questions about her possible extradition to Italy to serve her 28Â 1/2 - year sentence , handed down in absentia , since she has been in the United States throughout the retrial .

But Simon said it was too early to talk about extradition since there is still an appeals process to go through , which will probably last another year .

Citing privacy and confidentiality issues , State Department spokeswoman Marie Harf declined to say whether Italy has requested Knox be extradited .

Knox , 26 , told ABC she would fight every step of the way .

`` I will never go willingly back to the place where I -- I 'm gon na fight this until the very end , '' she said .

Asked how she was coping with the situation , her attorney highlighted her strength of character .

`` While she accepted that very difficult news , she has rebounded . She has shown great resilience and fortitude . And with a great deal of family support , they 're going to go forward and appeal what we would characterize as a completely unjust conviction , '' Simon said .

The attorney argued there was `` no evidence '' implicating his client in the murder and never had been , adding that it was `` incomprehensible '' that the court had found her guilty .

Sollecito stopped near border

Earlier Friday , Italian authorities stopped Sollecito near the border with Austria and Slovenia , Italian police told CNN .

Sollecito , who is not allowed to leave Italy while the legal process continues , was halted in the northern Italian town of Udine , police said .

The Slovenian border is less than 20 miles east of Udine , and the border with Austria lies about 55 miles to the north .

Sollecito 's lawyer , Luca Maori , said his client was indeed in Udine with his girlfriend . They were driving to the town of Treviso , where his girlfriend lives , and because of the snow had to stop , the lawyer said .

Maori told CNN it was not Sollecito 's intent to flee the country .

Prosecutors said the couple killed Kercher , a British student , in November 2007 . Sollecito was sentenced to 25 years in prison . Both denied murder .

Kercher , 21 , was found partially nude in a pool of blood in the house she shared with Knox in the picturesque town of Perugia , where both women were exchange students .

But despite years of courtroom battles over her death , many aspects of the crime still remain unexplained .

` Journey to the truth '

On Friday morning , Kercher 's siblings spoke in Florence about their family 's long ordeal .

Her sister , Stephanie Kercher , said the family might never know exactly what happened on the night of her death .

`` I think we are still on the journey to the truth , '' she said . `` I think it may be the fact that we do n't ever really know what happened that night , which is obviously something we will have to come to terms with . ''

Lyle Kercher , Meredith 's brother , said the family may have to wait until spring 2015 for a final resolution , since the verdicts reached Thursday can still be appealed at Italy 's Supreme Court .

`` Nothing is going to bring Meredith back , nothing will take away the horror of what happened to her , '' he said .

`` The best we can hope for is finally bringing this whole case to a conclusion , having a conviction , and everyone can move on with their lives . ''

If the Supreme Court upholds the murder conviction , he expects to see Italian authorities make an extradition request to the United States so that Knox serves her sentence in Italy , he said .

Stephanie Kercher said that she had been told of a letter written by Knox to the Kercher family but that she had not seen it .

She also appeared to rule out meeting with Knox in the future , despite the American 's overtures to the family and whatever the final outcome of the case .

`` We 've asked to have our wishes respected in that we would like to be together as a family to remember Meredith , '' she said . `` A lot has happened over this length of time . It would be very difficult to meet someone having had all that happen . ''

Read more : Six things to know about Amanda Knox retrial verdict

Pair first convicted in 2009

Knox and Sollecito were first convicted in 2009 , but those charges were overturned on appeal in 2011 and the pair were freed , having spent four years in prison .

In March of last year , Italy 's Supreme Court overturned the pair 's acquittals , leading to the retrial that resulted Thursday night in their convictions for murder being reinstated by a Florence appeals court .

Knox , who remained at home in Seattle , Washington , while the retrial was held , said in a written statement Thursday that her conviction would bring no consolation to the Kercher family .

Presiding Judge Alessandro Nencini has 90 days to write his arguments behind the jury 's ruling . Once that is out , lawyers have 90 days to appeal .

Hada Messia reported from Florence , and Laura Smith-Spark wrote and reported in London . CNN 's Deanna Hackney also contributed to this report .

@highlight

NEW : The U.S. State Department wo n't say whether Italy has requested extradition

@highlight

Amanda Knox says she will fight to the end , ` wo n't go willingly ' to Italy

@highlight

Knox 's attorney says it is too early to talk about extradition to Italy

@highlight

Raffaele Sollecito is stopped near the border with Austria and Slovenia , Italian police say